Summer School "Ecology and Society: Frontiers and Boundaries" / 3 - 7 June 2019

Exploring the 7th Continent with a microscopic focus

In 2015, more than 300 million tons of plastic were produced worldwide (reference from Plastics Europe). Jambeck et al. estimated that 2 to 5% of this amount reaches the oceans each year, thus implying several million tons of plastic1. In 2013, Rochman et al., in the journal Nature, alreadysuggested "classifying plastic waste as hazardous"2. Today, plastic pollution has been recognized by the scientific community as a global threat to the environment although the scope of its effects is still unknown.

The goal of the scientific component of the Expeditions 7e Continent is to appraise the extent of plastic pollution in the subtropical gyres in order to evaluate its potential impacts on the studied ecosystems. The 7th Continent surveys, conducted in May 2014 and May-June 2015, took place in the oceanic gyre in the North Atlantic Ocean.

The microplastics collected in the open ocean present very advanced state of weathering conferring them particular properties. The physicochemical characterisation of microplastics by infrared, electron microscopy and micro-topography is presented. The fragmentation of microplastics is discussed including a mathematical model of fragmentation. The formation of micrometric and nanometric particles evidenced under laboratory conditions encourage the effort to develop new methods of detection and quantification of plastic particles smaller than 300 µ in natural samples. This certainly will imply the development of new protocols. This would greatly help our understanding of the fate of microplastic in oceans.

1.            Jambeck, J. R.; Geyer, R.; Wilcox, C.; Siegler, T. R.; Perryman, M.; Andrady, A.; Narayan, R.; Law, K. L. Plastic waste inputs from land into the ocean. Science 2015, 347 (6223), 768-771.

2.            Rochman, C. M.; Browne, M. A.; Halpern, B. S.; Hentschel, B. T.; Hoh, E.; Karapanagioti, H. K.; Rios-Mendoza, L. M.; Takada, H.; Teh, S.; Thompson, R. C. Classify plastic waste as hazardous. Nature 2013, 494 (7436), 169-171.



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